The present invention relates generally to a toilet tank flapper which has a short flush and a long flush capability. More particularly, the adjustable flapper uses a moveable weight which, if activated, will temporarily reduce the turning moment arm of the flapper for ensuring a long flush.
It is a well known fact that a large use of water in most households, and in many office buildings, is for flushing toilets. Because the flushing is typically carried out with the full capacity of the water in the water tank, the water usage is often wasteful and not required; such as when flushing liquid wastes. For water conservation reasons considerable interest has been centered on designing flushing systems and mechanisms that uses a short duration flush for liquids and a longer duration flush for solids (i.e. a dual-flush toilet).
Examples of prior art dual-flush mechanisms, which afford a degree of user control over the amount of water used per flush, are U.S. Pat. Nos. 3,935,598, 4,225,987, 4,433,445, 5,129,110, 5,205,000 and 5,524,297. All of the above references, however, lack one or more necessary elements for successful wide utilization in the industry. That is, these prior art references may be prohibitively expensive, too complicated to install, maintain or operate, require the user to hold down the handle for several seconds during the flushing cycle, or may be difficult to retro-fit into existing toilets.
What is needed is a flushing mechanism or system which will provide a dual-flush capability and which does not have the above-mentioned disadvantages.
In one embodiment, a pivoting flapper valve assembly, set for a normally short flush, is provided for use in a flush tank. The flapper assembly comprises a weight, which shifts back and forth relative to the assembly""s pivot point. The assembly further comprises an actuator to trap and release the weight, resulting in either a short flush (when the weight is remote from the pivot) or a long flush (when the weight is close to the pivot). The flapper assembly is engageable through a resistance force, for selectively triggering the actuator, shifting the weight and resulting in a long flush.
More specifically, the assembly includes flush sustaining means preset to maintain the flapper assembly in the open position for a short time (i.e. a short flush). The assembly""s shifting weight, or turning moment arm shifting means, reduces the turning moment arm of the assembly when it shifts closer to the pivot, thereby causing the flush sustaining means to hold the assembly open for a longer time (i.e. long flush).
In a preferred embodiment, the moment arm shifting means comprises a longitudinal guide mounted for displacement with the assembly, a weight slidably constrained within the guide and retaining means (releasable by the resistance force) to retain the weight at the end of the guide furthest from the assembly""s pivot point. In one embodiment of the invention, the retaining means comprises a magnetic coupling device. In another embodiment, the retaining means comprises a pivoting lever mechanism.